Recognizes a protein of a disulfide-linked 120kDa dimer, identified as CD27 (Workshop VI; Code 6T-028). CD27 is expressed on the majority of peripheral T cells, medullary thymocytes, memory-type B cells, and natural killer cells. It is a transmembrane phosphoglycoprotein that belongs to the tumor necrosis factor receptor (TNFR) superfamily. CD27 binds to its ligand CD70, a member of the TNF family, and induces T-cell co-stimulation and B-cell activation. It also interacts with TRAFs and is involved in activation of NFB and SAPK/JNK and induces apoptosis.